In the manufacture of an electronic device, a processing of forming an opening such as a hole or a trench in a region containing a silicon atom and an oxygen atom, for example, a region made of silicon oxide (SiO2) may be performed. Generally, in such a processing, the corresponding region is etched by exposing the processing target object to plasma of a fluorocarbon gas, as described in U.S. Pat. No. 7,708,859.
Further, there is known a technique of etching a first region containing a silicon atom and an oxygen atom, for example, a first region made of silicon oxide selectively with respect to a second region made of a material different from the first region. As an example of such technique, a SAC (Self-Aligned Contact) technique is known. This SAC technique is described in Japanese Patent Laid-open Publication No. 2000-307001.
A processing target object to be processed by the SAC technique has a first region made of silicon oxide, a second region made of silicon nitride and a mask. The second region is provided to form a recess therein, and the first region is provided to fill the recess and cover the second region. The mask is provided on the first region and is provided with an opening above the recess. In the conventional SAC technique, plasma of a processing gas containing a fluorocarbon gas, an oxygen gas and a rare gas is used to etch the first region, as described in Japanese Patent Laid-open Publication No. 2000-307001. By exposing the processing target object to the plasma of this processing gas, a portion of the first region exposed through the opening of the mask is etched, so that an upper opening is formed. Further, as the processing target object is exposed to the plasma of the processing gas, a portion of the first region embedded in the second region is etched in a self-aligned manner. Accordingly, a lower opening continuous to the upper opening is formed in the self-aligned way.
Patent Document 1: U.S. Pat. No. 7,708,859
Patent Document 2: Japanese Patent Laid-open Publication No. 2000-307001